Hydrogen peroxide sterilization process and device

ABSTRACT

This invention concerns a hydrogen peroxide sterilization device, with injection of hydrogen peroxide vapour, provided with a vaporizer that feeds a sterilization chamber, with a dose that varies in function of the control performed by a computer or control unit. The vaporizer works with a pressure inferior to the atmospheric one and is heated by an electrical resistance heater, or by micro-waves. All the vaporization process is made in vacuum, by heat or ultra-sounds. The filling of the sterilant agent is made drop-by-drop by a capillary tube which transforms the liquid into a pulverized gas. The computer controls the electrical valve following the dosing pump from the pressure and/or temperature information that comes from various pressure and/or temperature sensors, whereby the pressure inside the chamber is maintained during the sterilization process in a constant predefined value, appropriate to use simple cellulose-base paper or paper composed to the packaging of the devices. The invention also refers to the hydrogen peroxide sterilization process that uses the referred device. The present invention is also appropriate to sterilize cork stoppers and stomatology material in chambers of reduced size, or other suitable materials for sterilization in bigger chambers. Based on the invention it is possible to create the REGISTOMETER FOR EVALUATING BIOLOGICAL INDICATORS AND CHEMICAL INDICATORS for laboratory studies of biological death and color change of chemical indicators, with hydrogen peroxide as sterilization agent.

The invention refers to a process and device for the hydrogen peroxide sterilization and it is based on the hydrogen peroxide vapour injection into a sterilization chamber with a temperature between 20° C. and 70° C. The process takes place in a chamber with two doors (with sanitary barrier) warmed between 20° C. and 70° C.

PREVIOUS INVENTIONS

Document WO 03072150 discloses a vapour generation unit which receives an aqueous hydrogen peroxide solution and includes a desiccant cartridge product.

Document EP1764115 describes a sterilization system which includes a hydrogen peroxide generator. It has a space for the introduction of the hydrogen peroxide in a treatment space and dehumidifier. It is important to note that there is a dehumidified air passage between the dehumidifier and the treatment space.

Document CA2519664 describes a sterilization process where the hydrogen peroxide solution is dripped from an injector into an evaporator during 3 minutes with a flow of 5 g/minute. The working chamber is filled with hydrogen peroxide after the reduction of the inside humidity from 1 to 10%. The sterilization occurs thanks to the hydrogen peroxide saturation inside the working chamber.

It is necessary to mention the technical documents in EP 06398011 application filed by the present applicant referring to a hydrogen peroxide sterilization device. According to that patent application, the extracted hydrogen peroxide from the chamber is burned thanks to a high tension inside a burner.

The present patent application results from an improvement and development of the invention described in patent application EP 06398011.

ADVANTAGES OF THE DEVICE OF THE PRESENT INVENTION

-   -   The drop-by-drop vaporization device has advantages compared to         the existing ones, as the precision obtained with the sterilant         agent dripping, using a capillary tube in the vaporizer and the         doses variability applied through a computerized control system,         which monitors the functioning of the device through various         pressure and temperature probes. The dosing system is not made         by only one dose system as it happens in other sterilizers.     -   The vaporizer vaporizes in 30 seconds a total of 2.5 ml of         hydrogen peroxide. It does not work necessarily in the         saturation.     -   Concerning the injection, the injection device does not have a         syringe injector but a capillary tube inside the vaporizer,         which transforms the liquid into pulverized gas;     -   The invention sterilization process occurs after the pressure         within the vaporizer reaches 1 mbar and all the sterilization         process is performed in vacuum;     -   The invention vaporizer is physically opened to the chamber, and         there is no valve between the vaporizer and the chamber;     -   In the invention device, the vaporizer is part of the chamber;     -   The control system is not based on the relative humidity, but it         is based on the chamber pressure.

DRAWINGS DESCRIPTION

The invention is now described as a non limitative example with reference to the attached drawings:

FIG. 1 shows a device scheme drawing which allows accomplishing the sterilization process according to the invention.

FIG. 2 is a graphic depicting the device functioning with the pressure evolution in the vaporizer depending on the time.

DETAILED DESCRIPTION

Referring to FIG. 1, the perforating unit (8) is composed by a drawer (8A), a recognition sensor (BB), a perforating cylinder (8C) and a closing drawer cylinder (8E). The drawer where the sterilant agent recharge is placed works with an electric and/or pneumatic cylinder mechanism.

The sensor (8B) reads and accepts the sterilant agent recharge, and the recharge is used according to the manufacturer instructions.

After the recharge has been recognized, the drawer (8A) is closed and the needle (8D) perforates the recharge. This needle works thanks to a mechanical and/or electrical system. After the perforation, the sterilant agent is pumped by the pump (7) and placed into the tank (6F).

The sterilant agent is removed from the tank (6F); thanks to a dosing pump (5) the liquid passes through a vaporization valve (4E) which introduces the hydrogen peroxide into the vaporizer capillary tube (4D). The sterilant agent tank (6F) has a float (6B). The level of sterilant agent is controlled by a level sensor (6A).

The sterilant agent vaporization is dripped and is obtained by a new device which includes vaporizer (4G), within which there is a capillary tube (4D) heated by an electrical resistance heater (4A), is fed by a dosing pump (5).

As the vaporization is dripped, it is possible to dosing small vapour quantities from the vaporizer chamber (4G) to the sterilization chamber (1A).

The process is developed inside a sterilization chamber (1A) with two doors (with sanitary barrier) heated between 20° C. and 70° C. in order to achieve a biological kill inside a “PCD” with 10 meters length.

This vaporizer (4) is essentially based on a chamber (4G)—provided with an electrical resistance heater (4A)—needs to have a programming command, in order to control the opening/closing of the vaporizer valve (4E), after the continuous pressure calculation. Between the product entry valve (4E) and the vaporizer (4G) there is a device designed for the drop-by-drop vaporization. The dosing is ensured by an electrical valve (4E) at the entry of the vaporizer, commanded by a computer or control unit.

After being heated by the vaporizer (4G) the capillary tube (4D) is able to vaporize drop-by-drop with a programmed command by the computer.

The vaporizer (4G) is heated by an electrical resistance heater (4A) at a temperature between 80° C. and 200° C. The vaporizer (4A) has a pressure and/or temperature probe (4B) which sends the information to the control computer. The hydrogen peroxide is injected drop-by-drop into the vaporizer (4G), which is mechanically connected to the sterilization chamber (1A) by a clamp system with a Teflon tube (4F) which conveys the hydrogen peroxide and allows the entry of the vapour inside the chamber (1A) in the best conditions.

Between the dosing pump (5) and the vaporizer valve (4E) there is a return line of the sterilant agent.

Near the vaporizer entry valve (4E), there is an air removing system thanks to a vacuum pump (10A), which removes the air before starting the drop-by-drop injection. The gas passes through a burner (9C) with high-tension electrodes (9D).

The sterilization chamber (1A) has a pressure and/or temperature probe (11C e 1B) which informs the computer that controls the process.

According to the drawing 1, in order to achieve a drop-by-drop injection, the capillary tube (4D) has a length between 50 mm and 2500 mm with a hole from 1 μmm to 0.1 mm, which allows the drop-by-drop vaporization. The entry valve (4E) is controlled based in the value vaporized in each opening. There will be successive openings of the valve until reaching the established value for a pressure between 5 mbar and 155 mbar.

The dosing system has no air, which means that if there is less material inside the chamber for the same value of pressure, it will be necessary to inject more hydrogen peroxide. On the other hand, if there is more material inside the chamber for the same pressure value, it will be necessary to inject less hydrogen peroxide.

The sterilization is reached in lumen with 10 meters of length and 1 mm diameter with biological indicators Stearothermophilus inside a container inserted inside the lumen in a population of 1.2×10⁵ during the sterilization period between 80 and 2200 seconds (diffusion phase).

The dripping dosing system is ensured by a peristaltic pump (5) that starts the pumping between 10 and 80 seconds before the injection, in order to remove all the air in the tubes. After this pumping period, and air removal from the tubes, the vaporizer valves (4E) open with intermittent opening controlled by the pressure read in the sterilization chamber (1A).

With this process, there is a curve of vaporization with an entry similar with that shown on the drawing 2. The diffusion period occurs between 80 and 2200 seconds with a pressure between 5 and 155 mbar.

Modifications can be made to the disclosed sterilization device, maintaining the functioning principle in the attached claims, for example modifications with equivalent element, which fall in the scope of this invention. 

1-18. (canceled)
 19. Hydrogen peroxide sterilization device with hydrogen peroxide vapour injection, provided with a vaporizer (4G) that feeds a sterilization chamber (1A), characterized in that the feeding is made with a dose varying with the control function performed by a computer or control unit, to enable the use of simple cellulose-based paper packaging, composed paper or other absorbent; the vaporizer works with a pressure inferior to the atmospheric one and it is heated by an electrical resistance heater (4A), or by a micro-wave system; all the vaporization process being made in vacuum to a chamber (1A) at a pressure between 0.0001 mbar and 500 mbar; the filling of the sterilant agent, supplied from a tank (6F) with controlled temperature, is made drop-by-drop by a capillary tube (4D), which transforms the liquid into a pulverized gas, where ultra-sounds can be used for the vaporization, the computer controls the electrical valve (4E) following the dosing pump (5) taking into account the information concerning the pressure and/or temperature coming from various pressure and/or temperature sensors (11C, 11B), and the pressure inside the chamber (1A) is maintained during the sterilization process at a constant predefined value, even in the presence of absorbent material (simple cellulose-based paper or composed paper, as packaging for the devices to be sterilized).
 20. Device according to claim 19, characterized by a vaporizer (4G) that is able to vaporize a total of 1-6 ml of hydrogen peroxide for a period of 3-100 seconds, which is injected to a sterilization a chamber (1A) where the pressure evolutes to values of about 5 to 655 mbar, the device being also characterized in that it has various pressure and/or temperature sensors, namely in the vaporizer (4G), in the sterilant agent tank (6F) and in the sterilization chamber (1A).
 21. Device according to claim 19, characterized in that the hydrogen peroxide vapour injection in the sterilization chamber (1A) occurs in a temperature value between 20° C. and 70° C., after the vaporizer (4G) being heated by an electrical resistance heater (4A) to a temperature between 30° C. and 200° C., said vaporizer comprising pressure and/or temperature and humidity probes that send the information to the control computer.
 22. Device according to claim 19, characterized in that the hydrogen peroxide is injected drop-by-drop into the vaporizer (4G), which is mechanically connected to the sterilization chamber (1A) by a clamp system and a Teflon tube which leads the hydrogen peroxide in a gaseous state to the sterilization chamber (1A), said device comprising a return line of the sterilant liquid between the dosing pump and the vaporizer valve, said device further comprising a vacuum pump capable of removing the air before the start of the drop-by-drop injection in the sterilization chamber.
 23. Device according to claim 19, characterized in that it has near this entry valve (4E) in the vaporizer, an air removing system thanks to a vacuum pump (10A) which removes the air from the chamber before the start of the drop-by-drop injection of hydrogen peroxide in the vaporizer which is mechanically connected with the sterilization chamber (1A), said air passing through a plasma generator (9C) at high temperature with high tension electrodes (9D) breaking the hydrogen peroxide in water, oxygen and free radicals by a plasma effect.
 24. Device according to claim 19, characterized in that it has a capillary tube (4D) between 5 mm and 550 mm of length with a hole of de 2 μmm to 1.5 mm which injects the hydrogen peroxide drop-by-drop into the vaporizer, comprising an entry valve (4E) in the vaporizer that is controlled based on the value vaporized in each opening, having successive openings of the valve (4E) until the vaporization established value is reached in order to obtain a pressure between 5 mbar and 655 mbar.
 25. Device according to claim 19, characterized in that it comprises a temperature control system between −10° C. and 22° C., performed by an assembly of ventilator and peltier plate in a tank of sterilant agent (6F) or in the container support of the sterilant agent, said device being further characterized in that the sterilant agent pumping is made by a peristaltic pump (5) or other, between the tank (6F) of the sterilant agent and the vaporizer (4G) with 1 to 800 seconds before the injection, in order to remove all the air in the tubes.
 26. Device according to claim 19, characterized in that the sterilant agent is pumped by the pump (7) and positioned in the tank (6F), from which is removed by a dosing pump (5) that inserts the hydrogen peroxide in a capillary tube (4D) located inside a vaporizer (4G) heated by a resistance (4A) or other means, or by being removed directly from the container and injected in the vaporizer, said device being further characterized in that the valve (4E) opening to the vaporizer (4G) occurs after said pumping period and after the removal of the air from the tubes, with intermittent opening controlled by the pressure and/or humidity read in the sterilization chamber (1A).
 27. Device according to claim 19, characterized in that it is feed with sterilant agent from a recharge pumped to the tank, the drawer (8A) or support has a sensor (8B) that recognizes the packaging through the use of RFID (TAG, microchip or other), which controls the date and validity of the packaging; the automation interacts with the microchip values, changing the vaporization value drop-by-drop according to the product age, and the characteristics read online on a hydrogen peroxide concentration reader, said device being further characterized in that it has a plasma generator that catalyzes the hydrogen peroxide vapour at the chamber exit by plasma effect, which plasma generator is or not an integral part of the chamber.
 28. Device according to claim 19, characterized in that it is able to sterilize stomatology material in a reduced size chamber, to sterilize cork stoppers commonly used in wine bottles or other bottles and to sterilize endoscopes and videoscopes.
 29. Device according to claim 19, characterized in that it is has a Penetration Test cycle of the sterilant agent, a cycle of Leak Test, a cycle that incorporates the Penetration Test and the Leak Test in a single one, and cycles dedicated to different materials.
 30. Device according to claim 19, characterized in that it is prepared to perform the functions of a RESISTOMETER FOR EVALUATING BIOLOGICAL INDICATORS AND CHEMICAL INDICATORS for laboratory studies of biological death and color change of chemical indicators using hydrogen peroxide as sterilization agent.
 31. Process for the sterilization and/or disinfection through hydrogen peroxide with concentration of 1% to 99% characterized in that it uses a device according to claim
 19. 